Electric machine



July 28, 1925.

hvehtor: 'Max Schuler,

- EMM/Clif l His Attorneg.

Reissued July 28, 1925.

UNITED STATES l A Re. 16,126 PATENT OFFICE.

MAX SCHULER, OF NEUMUI-ILEN, NEAR KIEL, GERMANY, ASSIGNOR, BY MESNE AS- SIGNMENTS, 'IOv GENERAL ELECTRIC COMPANY, A CORPORATION 0F NEW YORK.

ELECTRIC MCHINE.

OriginalNo. 1,453,083, dated April 24, 1923, Serial No. 127,682, filed October 25, 1916. Application fory reissue led November 17, 1924; wSerial No. 750,465.

To all whom it may concern.'

Be it known that I, MAX SCHULE'R, a subject ofthe Emperor of Germany, residing in Neumuhlen, near KielGermany, have invented certain new and useful Improve- -ments in Electric Machines (for which I vhave filed an application for German patent September 22, 1915), of which the following is a specification. A

With electric machines `having a great number of revolutions and great circumferential velocities of thev armature. or with considerable output, it often proves diiiicult to sufficiently cool the armature by air. The electric losses comprise the heating of the armature by air friction andthe work of forcing the necessary cooling air through the parts to be cooled. Also the airused v for cooling is heated by Athe/Ventilating apparatus and thefairpfriction, and the cooling action of the air is thereby diminished. For such reasons, it becomes necessary to increase the ventilation, the result being a correspondingy increase also of the, power consumed in the'ventilation and a diminution of the efliciency of the machine. With high-speed machines, such, for instance, as high-frequency transformers, it may even become necessary to reduce the number of revolutionsof thev armature 'more than its stability requires, and more .than it is vdesirable from the electric point of view in order to preventtoo great a rise in temperature.v It is true that it has been proposed to have such machines run in vacuo, but that will not bring the desired result, for while it is true that the air friction will diminish proportionately the air-pressure, the heatconductivity of the air will be lowered in the same proportion.

For these reasons the armature of electric machines of this kind is, according to the present invention, made to run in hydrogen, the physical constants of which are much more favorable than those of the air. Since the power consumed in ventilation is diminished in proportion to the specific weight, itamounts, with hydrogen, to only the fourteenth part of that of the air. Furlthermore the viscosity-of hydrogen is only half that of the air. On the 'other hand the heat-conductivity of hydrogen is 7% times that of the air and the specific heat of 1 gram of hydrogen is about 14% times that of 1 gram of'air. At the same time we obtain, with machines running in contact with hydrogen, the further great advantage that metals and oils do not enter chemical" combinations with f hydrogen; consequently@ the collectors and the slip rings remain always bright, n'or will the oils in the bearings turn resinous or become altered.

In certain cases furtherl special advanf tages are attained. With the already mentioned highfrequency transformers for wireless telegraphy the casing and enclosing of the hydrogen produces a very considerable silencing action, so that the reception of incoming signals is facilitated.

The hydrogen is intended to act as a medium for the carrying-ofi' of heat from the rotating armature to the casing. With this in view, the magnet-shell may be constructed as a gas-tight casing ork the machine may be fitted in a separate gas-tight container. The container ymust yield heat to the air for which purpose it may be provided with cooling ribs. Should the surface, however. not be suiiicient forthe carrying-of of the heat, the shell may be provided with suitable water-cooling or heatv I radiating means. The arrangement may 6 also be made in such manner that the armature. acts as a fan for circulating the heated` hydrogen through external or internal cooling devices and again drawing the cooled hydrogen into the machine.'

In the subjoined drawing, Figures 1 and 2 arelongitudinal vertical sectional views of two embodiments ofthe invention.

U in Fig. 1 being an electric machine, for instance, a transformer for high-frequency current. This machine is mounted in a casingo, closed by a lid Y). This casing is-airtight and filled with hydrogen through, openings (not shown). A. pressure-gauge al permits of reading the pressure andfor a known pressure aL a normal temperature-fthe reading of the temperature of the vhydrogen. The pressure-gauge therefore be rovided, beside the pressurescale, also with a temperature-scale. The transformer U is a normally ventilated electric machine. Byenclosing thetransformer may multiple of that of the air, and the machine may therefore be considerably'more bearings Without anyf air entering the casing a.

n the embodiment of F 1g. 2, a fan 'i is provided on the shaft la of the machine U,`

which fan is placed immediately in front of a lateral opening c of the casing a. Upon the `o posite side of the casing there is provide an opening Z. The opening lc is closed by a lid m having an openmg fn.. The openings Z and 'n are connected to eachother by a pipe o, inserted gas-tight in Saidopenings Z and n. This pipe leads through any cooling device, for instance, a rece tacle f1., through Which cooling water is ed. The casing a and thehpipe o are filled with hydro en as before. When the machine is wor 'ng, the fan z' will suck hydrogen out of the pipe o, said hydrogen being delivered For carrying off theheat from submitted to, the more heat will be carried i ofi' by it, but the greater will be the power consumed in ventilation with the same machine. Consequently one gains b an alteration of the pressure of the hy regen, a means for limitlng the heating of the machine, making good the electric losses, more fully utilizing the machine, and attaining higher eiiiciencythan heretofore possible.

Vhat I` claim is: y

l. In combination, a casin g having an electric machine therein; hydrogen gas in said casing as a cooling medium; and means Within said casingl for cooling the hydrogen. `"2. In combination, a casing having a dynamo electric machine therein; hydrogen gas in said casing as a coolingr medium; and means for cooling the hydrogen.

In witness whereof, I have hereunto set my hand this 27 day of October, 1924.

DR. MAX soHULER. 

